The present invention relates to an electrochemical storage device having electrode plates of different polarity alternately stacked on one another, each electrode plate being formed from an electrode framework having a current-collecting lug arranged thereon, the individual, identically polarized current-collecting lugs being connected in an electrically conductive fashion with their weld-on rims arranged on their free end region to a terminal yoke extending parallel to the electrode stack formed from the electrode plates and transverse to the flat side of the current-collecting lugs. The present invention also relates to a method for producing an electrochemical storage device which has a plurality of electrode plates formed in each case from an electrode framework having a current-collecting lug welded on the end, the individual, identically polarized current-collecting lugs being connected in an electrically conductive fashion with their weld-on rims arranged on their free ends to a terminal yoke. Each of the current-collecting lugs is connected at the end by in each case one electrode framework to an electrode plate, the electrode plates being stacked on one another with the intercalation of various parts such as separators, recombiners etc. transverse to their flat irons to form an electrode stack. The electrode stack is insulated on the outside and inserted into a housing. The current-collecting lugs respectively of the same polarity are connected with their weld-on rim arranged on the free end region to a terminal yoke assigned to this polarity and on which a terminal pillar is arranged.
The fundamental electrochemical storage device of the above-described generic type has electrode plates of different polarity stacked on one another, each electrode plate being formed from a current-collecting lug having an electrode framework arranged on its one end region. The electrode plates are stacked on one another alternately to form an electrode stack, with separators being arranged between electrode plates of different polarity and recombiners being arranged between two successive electrode plates of the same, negative polarity, and electrode plates of the same polarity being connected to one another in an electrically conductive fashion via a terminal yoke. The current-collecting lugs are welded to the terminal yoke by electrical resistance welding along a weld-on rim arranged at their end region, for the purpose of electrically connecting the electrode plates of the same polarity. In order to simplify the welding, the weld-on rims of the current-collecting lugs are bent transverse to the flat side of the other current-collecting lug, preferably by an angle of approximately 90.degree., the weld-on rim being provided with welding knobs in order to improve the welding result. In spite of these welding knobs, defective or poor welds keep recurring, which particularly in the case of high-quality electrochemical storage devices such as, for example, batteries for space, signify rejection.
An object of the present invention is to improve a fundamental storage device of the initially described type to reduce rejections due to welding the current-collecting lugs to the terminal yoke. Furthermore, a method for producing it is to be developed.
This and other objects are achieved by the present invention which provides an electrochemical storage device comprising electrode plates of different polarity alternately stacked on one another to form an electrode stack, each electrode plate including an electrode framework and a current-collecting lug arranged thereon, the current-collecting lugs having weld-on rims arranged on a free end region. A terminal yoke extends parallel to the electrode stack and transverse to a flat side of the current-collecting lugs, with individual identically polarized current-collecting lugs being connected in an electrically conductive fashion with their weld-on rims to the terminal yoke. The terminal yoke has a flat side remote from the electrode stack, and a transverse slot at a location of a current-collecting lug into which the free end region of the current-collecting lug at least projects. The current-collecting lug is attached to the terminal yoke in the region of the flat side of the terminal yoke.
The above-stated objects are also achieved by an embodiment of the present invention which provides a method for producing an electrochemical storage device comprising forming a plurality of electrode plates by welding a plurality of current-collecting lugs respectively on an end of an electrode framework, stacking the electrode plates on one another with the intermediate positioning of elements transverse to flat sides of the electrode plates to form an electrode stack, and insulating outer regions of the electrode stack. The electrode stack is inserted into a housing. The weld-on rims of the current-collecting lugs are plugged into transverse slots of the terminal yoke. In an electrically conductive manner, the individual, identically polarized current-collecting lugs are connected to a terminal yoke assigned to this polarity, the current-collecting lugs being connected to said terminal yoke by weld-on rims of free ends of the current-collecting lugs to the terminal yoke, the terminal yoke having webs between the transverse slots, and a terminal pillar. The step of connecting the current-collecting lugs to the terminal yoke includes electrical resistance welding the weld-on rims of the current-collecting lugs to the webs of the terminal yoke.
Due to the design according to the invention of the current-collecting lug and the terminal yoke, the weld of the terminal yoke with the weld-on rims of the current-collecting lug, which weld is easy to produce, has a high strength and low contact resistances, these properties being ensured even in the case of high vibration loads on the electrochemical storage device.
A further advantage is that, with a welded connection of the terminal yoke and the current-collecting lug as against a screwed connection, a plurality of components are spared and thus the mass of the storage device is reduced, the overall height of the storage device is reduced and the contact resistance between the current-collecting lug and terminal yoke is lower. On the production side, there is the further advantage that the production of the storage device according to the invention can be automated since, inter alia, the welding zones are easily accessible after the assembly of the cell stack. The result is that, despite the higher quality of the electrochemical storage device and despite reduced rejection during production, there is a reduction in cost during production of the electrochemical storage device and a shorter production time.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.